This paper argues for two claims. (1) In his biological views, Kenelm Digby tries to reconcile aspects of an Aristotelian theory of composite substance with early modern corpuscularianism. (2) From a methodological point of view, he uses the Stoic-Epicurean epistemology of common notions in order to show the adequacy of his conciliatory approach. The first claim is substantiated by an analysis of Digby’s views on the role of mixture and homogeneity in the process of animal generation. The second claim is (...) substantiated by an analysis of Digby’s views on the role of the concept of quantity in the evaluation of scientific hypotheses. Both arguments make use of the context of Digby’s philosophy: the first argument draws on his background in the work of early modern corpuscularian Aristotelians such as Daniel Sennert; the second argument draws on his background in the epistemology of Pierre Gassendi. (shrink)